‘They’re Everywhere’: The Emerald Ash Borer Strikes Vermont


Vermont Agency of Natural Resources
Bark damaged by the Emerald Ash Borer.

MIDDLEBURY — Two months ago, both the Vermont Department of Forests, Parks and Recreation and the Vermont Agency of Agriculture, Foods and Markets reported a sighting of Emerald Ash Borers in northern Orange County, Vermont. An exotic beetle native to China, eastern Russia, Japan and Korea, the Emerald Ash Borer (EAB) is an invasive species that targets all types of ash. First found near Detroit in 2002, the Ash Borer has spread rapidly throughout North America, and its invasion in Vermont has long been anticipated. None of Vermont’s native ash trees are known to be resistant to the pest.

“They’re everywhere,” said Tim Parsons, Middlebury College’s Landscape Horticulturist, of the ash trees on campus. “I can stand on the front steps of the Chapel and point to four, and I can stand on the back steps and point to eight more.” The main campus of Middlebury College has 182 ash trees, constituting roughly 8.7 percent of the campus’ tree community. On the Green Mountains, ash makes up about 10-15 percent of trees, but they are not as congregated as they are on Middlebury’s main campus.

Since 2010, Parsons has taught a J-term class every few years called “Trees and the Urban Forest,” which centers on the ecological and aesthetic value of the forest in an urban setting. In past years, the class has developed emergency preparedness plans against the invasion of the Emerald Ash Borers for both the town of Middlebury and the College. In 2015, the class made a plan to survey all the ash on campus, devise strategies for treatment or removal of ash trees and consider options for replanting. On a website called EAB at Middlebury College (go/EAB), two students from the 2015 J-term class estimated the total cost for the injection, removal, and replacement of ash trees on campus would reach approximately $500,000.

A map of trees on campus, made by a group of students in 2002 but last updated in January of 2014, shows congregations of ash behind Ross commons, a grove of almost exclusively ash in front of the Atwater commons house near the Trail Around Middlebury and a patch of ash behind Proctor, most of which was removed before the construction of the Ridgeline Suites. Other conspicuous spots of ash include three large structures near Forest Hall and several in the northwest corner of Battell Beach, on which many students hang hammocks on warmer days. Though ash accounts for less than 10 percent of the campus’ tree population, small stands of ash trees often serve as prominent landscape features, meaning that their removal will result in noticeable gaps in the Middlebury landscape.

Nevertheless, the position of many ash trees near key structures such as residence halls and dining halls may necessitate their removal. Smaller than a penny, an ash borer will bore through the inner bark and likely result in the death of entire trees. A survey in 2015 by students in Parsons’ class located 658 “hazardous” trees found within 50 feet of roads, sidewalks and parking lots.

Once an ash has been infested, it has on average between two to four years to live. Out of concern for the safety of students and members of the college community, landscape facilities will likely have to remove infested trees before a year has passed.

As Parsons explained with a touch of cynical humor, “One of the definitions of a tree is that it’s a large plant that, when it falls on someone, may kill them.”

When implemented on a larger scale, however, mass-removals of ash may become detrimental to local flora and fauna. Professor Stephen Trombulak, a landscape ecologist, said that a drastic loss of ash trees “will mean that there will be a lot of dead trees in the forest, which will almost certainly alter all aspects of forest ecosystems, including but not limited to nutrient cycling, soil retention, abundance of species that specialize on dead and decaying wood, soil moisture content, soil temperature, fire intensity and frequency and the abundance and density of plant species that do well in forest gaps.”

The loss of large amounts of ash could have unexpected repercussions for other industries as well. For example, most Major League Baseball bats are made of ash because the hardwood is not inclined to splinter and shatter. Middlebury College’s own replicas of Gamaliel Painter’s cane, given out to all seniors at Commencement, are made of ash.

The most abundant use of ash by far is as firewood. It is possible that ash removed from campus in the near future may be burned in the biomass plant to provide energy for campus consumption. The invasion of this pest, however, brings with it quarantines and regulations on the transportation of firewood, which will almost certainly affect log prices in the area. 

Parsons’ approach is to wait until it is absolutely necessary to cut down the ash. Neither attempts at eradicating the ash borer nor removing all the ash in the area have been successful in the 31 other states that have been infested. It is estimated that only one percent of ash in an infested area survive, so efforts to regenerate ash seedlings and saplings in Vermont forests are crucial.

The Emerald Ash Borer camouflaged against a leaf.

“An ash borer’s immediate range is not very far. It could take them five, ten years to get here,” Parsons speculated. “Or they could get stuck to the windshield of a car and get here tomorrow morning.” One of the major pathways of travel for the Emerald Ash Borers is facilitated by humans, through interstate transport of infested firewood.

Key in deterring the spread of the Emerald Ash Borer will be observant and conscious Vermonters. The first report of the insect in Vermont was made by a forest manager in Orange County on the Vermont Invasives website.

Professor Trombulak suggested that “Vermonters should be responding to this issue by not moving potentially-infested firewood from one location to another, reporting sightings of EAB immediately and planting ash trees whenever possible in the hopes that the seed pool for those species can be maintained until an effective management plan can be implemented.”

Another method of response, Parsons said, is injecting infested trees biannually with pesticide, but such a short-term solution is neither cost-effective nor implementable on a large scale under facilities’ current budget. Though some are investigating the use of bio-controls such as woodpeckers or parasitic wasps to control ash borers as a “last-ditch effort” to combat the invasive species, the effectiveness of such measures has yet to be determined. Professor Trombulak says that “there is speculation that an increase in EAB will lead to woodpeckers and parasitic wasps feeding on EAB, which might control their populations.” However, he warned of the unpredictability of such an approach, as he is “not aware of any evidence that predator control has been shown in locations where EAB have been established for some time.”

Since its first sighting in the state on Feb. 20, the Emerald Ash Borer has been found in two additional Vermont counties. Tell-tale signs of an infestation include woodpecker damage to living trees in the form of smooth, light-colored patches on the outer bark, S-shaped galleries created by ash borers weaving back and forth underneath the bark and abundant D-shaped ash borer exit holes on the trunk of a tree.

Trees serve an essential, albeit often underappreciated, role in the Middlebury landscape. Parsons’ enthusiasm for the trees on campus is as clear as it is contagious. “I’d say I have about twelve [favorite trees on campus],” he admitted. “They’re like your kids—you can’t pick just one.”

“It’s heartbreaking,” Parsons said, grieving for the ash that we will undoubtedly lose in the next few years. “I can’t stress that enough.”